AB0445 THE BENEFICIAL EFFECTS OF THERAPY ON OBSTETRICAL OUTCOME AND PLACENTAL HISTOLOGY IN PATIENTS WITH ANTIPHOSPHOLIPID SYNDROME: THE EXPERIENCE OF A SINGLE ITALIAN REFERENCE CENTER
Authors: V. Canti, G. Inguscio, N. P. Tenace, R. Lucianò, R. De Lorenzo, M. B. Cilona, M. Pozzoni, P. I. Cavoretto, M. T. Castiglioni, P. Rovere-Querini
Journal: Annals of the Rheumatic Diseases (2022)

Background Abnormal placentation plays a crucial role in the pathogenesis of obstetric morbidity in antiphospholipid antibodies syndrome (APS). Placenta is the main target of aPL in obstetric APS, inducing placental thrombosis, inflammatory response and placental dysfunction. Standard treatment for APS patients during pregnancy includes low-dose aspirin (LDA) plus low molecular weight heparin (LMWH) and, in refractory cases, additional therapies such as hydroxychloroquine (HCQ). A systematic review of the literature has found five main pathological lesions in the placenta of APS patients: placental infarction, decidual vasculopathy, decidual inflammation, increase of syncytial knots due to syncytiotrophoblast death, and decrease in vasculosyncytial membranes. Objectives To analyze placental histology in a group of 23 spontaneously conceived pregnancies in patients with definite APS prospectively followed in a single Italian reference center. Methods We analyzed 25 placenta in 23 spontaneously conceived pregnancies in patients with definite APS prospectively followed in the ‘Pregnancy at risk’ multidisciplinary outpatient clinics at San Raffaele Hospital, Milan, Italy from January 2017 to May 2021. During each trimester of gestation, ultrasonography with Uterine artery Doppler velocimetry was performed. Histological analysis of the placenta was carried out after delivery and placental tissues were examined for the main aforementioned histopathological findings. Statistical relations among clinical and ultrasound evaluations during each trimester, therapeutic approach and placental histology were performed. Results 19/25 (76%) patients had primary APS, while 6 patients had APS secondary to SLE. All patients were treated with LDA and LMWH. HCQ was added in a group of patients with concomitant systemic lupus erythematosus (SLE) or in refractory APS. Mean placental weight was 441 ± 129 grams. Histological analysis of placental tissues revealed increased syncytial knots in 17/25 (68%) placenta, decreased vasculosyncytial membranes in 11/25 (44%), infarction in 8/25 (32%), presence of macrophages and decidual inflammation in 2/25 (8%), and atherosis or reduction of spiral arteries remodelling in 3/25 (12%) placenta. Moreover, we observed at least 2 concomitant placental lesions in 12/25 (48%) placentas. No statistical association between mean UtA-PI values and the number and type of placental lesions described at the histologic analysis were observed. We found a positive correlation between mean titer of aCL IgG, aβ2GPI IgG, aPS/PT IgM and/or aPS/PT IgG and number of placental lesions, and a significant association between aPS/PT IgM and/or IgG mean titer and presence of infarcted areas at placental histology. Moreover, in the placenta of patients treated with HCQ we did not observe any decidual inflammation at histology. Conclusion In our study we found some important clinical-pathological correlations between placental histology, clinical evaluations, ultrasound assessments and treatment received during pregnancy. Specifically, it is tempting to speculate that HCQ may have beneficial effects on pregnancy by decreasing the risk of deciduitis in patients with APS. Further studies on larger numbers of placenta in APS patients will be needed to confirm our findings. References [1]Viall CA, Chamley LW. Histopathology in the placentae of women with antiphospholipid antibodies: A systematic review of the literature. Autoimmun Rev. 2015 May;14(5):446-71. Disclosure of Interests None declared